On the Hailo.com blog Matt Heath has posted a series of articles about their transition from a "monolith" codebase out into a set of microservices for the Hallo app system.

Hailo, like many startups, started small; small enough that our offices were below deck on a boat in central London - the HMS President. Working on a boat as a small focused team, we built out our original apps and APIs using tried and tested technologies, including Java, PHP, MySQL and Redis, all running on Amazon's EC2 platform. [...] After we launched in London, and then Dublin, we expanded from one continent to two, and then three; launching first in North America, and then in Asia. This posed a number of challenges-the main one being locality of customer data.

They describe this customer data problem in a bit more detail with the issue mostly revolving around the geolocation of the user and their information. They talk about "going global" and the steps they took to make the move. In the three parts of the series, they explain the changes they made and why they were effective for their application:

• Starting Small
• A Cloudy Beginning
• Dealing with Complexity

They end the series with some links to other resources that help compliment the subjects mentioned and link to slides from a presentation around the same topic.